Susan Belar - Student Research Committee, Qom University of Medical Sciences, Qom, Iran.
Hanieh Hajian - Clinical Research Development Center, Hazrat Masoome Hospital, Qom University of Medical Sciences, Qom, Iran.
Seyedeh Zeinab Modarresy Mosalladarresy Mosalla - Clinical Research Development Center, Hazrat Masoome Hospital, Qom University of Medical Sciences, Qom, Iran.
Zahra Movahedi - Clinical Research Development Center, Hazrat Masoome Hospital, Qom University of Medical Sciences, Qom, Iran.

Background and Aim: Following the prevalence of severe acute respiratory syndrome-coronavirus (SARS-CoV۲) in the world, a type of severe involvement in children was reported as multisystem inflammatory syndrome in children (MIS-C) involving various organs, such as lung, skin, heart, kidney, gastrointestinal tract, and eyes, acute abdomen as a manifestation of this syndrome is rarely reported. To introduce children with MIS-C with fever and acute abdomen who underwent appendectomy. Case Report: Six children between the ages of ۸ to ۱۲ years (۳ boys and ۳ girls) presented with acute abdominal pain, fever, and vomiting, due to obvious tenderness and rebound tenderness in the right lower quadrant of the abdomen and other clinical and laboratory symptoms, ۴ of them underwent emergency appendectomy. Materials and Methods: Due to the lack of improvement in abdominal pain and the symptoms and problems in various organs in patients, such as heart (three cases of myocarditis, one case of pericardial effusion), kidneys (two cases of increased urea and creatinine), skin (four cases of skin rash), lung (six cases of pulmonary involvement and two cases of pleural effusion), gastrointestinal tract (abdominal pain and vomiting and three cases of diarrhea), and laboratory symptoms in the form of increased acute phase reactors and (D dimer ) and most cases of lymphopenia (six cases) and evidence of COVID-۱۹ infection (positive polymerase chain reaction [PCR] or COVID-۱۹ positive serology, or compatible imaging and laboratory symptoms), MIS-C was diagnosed and treated for these patients. Patients were treated with corticosteroids and intravenous immune globulin (IVIG) and enoxaparin and other medications and fortunately, all cases improved. In addition, the pathology report after appendectomy was appendicitis in most cases. Results: Four cases that showed clinical manifestations of acute abdomen underwent surgery without overall complications. In some of these patients, appendicitis was the cause of abdominal pain, and in some patients, inflammatory response to COVID-۱۹ (e.g. mesenteric adenitis) was the cause of pain and no mortality was reported. In most patients, inflammatory markers, such as CRP and ESR were elevated, and albumin levels were mildly decreased during admission and ferritin and D-dimer levels were abnormal in most patients. Four cases had cardiac involvement and all MIS-C patients were treated with steroids and IVIG, respectively. Also, no mortality was reported in patients treated with corticosteroids. Conclusion: Therefore, it is essential to note that in children with a complaint of abdominal pain and have symptoms in favor of an acute abdomen; attention should be paid to the symptoms of the involvement of other body systems due to (MIS-C).

Abdomen, Acute, Adult multisystem inflammatory disease, COVID-۱۹ related, COVID-۱۹